Original complaint
A department reported its exhaust fan was not working.
- No expected exhaust airflow at the reported area
- Roof inspection identified two belt-driven exhaust fans needing belts
- Fan motors/assemblies could be returned to operation after belt replacement
Measurements taken
- Fans serviced
- Exhaust fan #6 and #16
Diagnostic process
- 1Confirmed the affected department and gained roof access
- 2Identified the serving exhaust fan and inspected nearby belt-driven equipment
- 3Found failed/worn belt conditions on two fans
- 4Replaced both belts, restored operation, and returned to the occupied area to verify exhaust
Finding / confirmed status
Failed drive belts prevented normal fan wheel operation on the affected exhaust fans.
Repair / action taken
Replaced both belts, restarted both fans, and verified the originally reported exhaust system was operating from the occupied space.
Final operating readings
- Reported exhaust fan
- Operating after belt replacement
- Second fan
- Returned to operation
Technician notes
A motor sound on the roof does not prove airflow. Belt condition, wheel rotation, dampers, and actual exhaust at the space all matter.
- Verify the serving fan before repairing
- Inspect belt condition and pulley alignment together
- Confirm airflow at the occupied area after rooftop repair
Safety cautions
- Lock out fan power before removing guards or touching the belt drive
- Replace guards and verify clear rotation before restart
Safety note
HVAC work can involve high voltage, rotating equipment, pressurized refrigerants, and combustion systems. Use this site as a reference only. Follow the equipment manual, applicable codes, PPE, lockout/tagout, and current refrigerant rules. Field cases and troubleshooting paths are case-specific and are not OEM procedures or universal targets.